{{Tl}} and {{Tl2}} are simple macrotemplates used to display a template name as a link. Tl stands for Template link.

Tl2 differs in that it displays an arguably clearer result like {{Tlx}}, and also like takes the named parameters 'SISTER=xx' and 'LANG=ll', so that it may also be used to list and link to templates on other English and non-English language sister projects.

related

Nemachiyōtīlli:Tl2 displays with the same enhanced presentation, and also expands several 'placeholder' parameters to generate a sample template call.

{{Tl|template name to display}}
and
{{Tl2|template name to display}} -- local link, just like Tl.
or
{{Tl2|SISTER=V:|template name to display}} -- displays a template on Wikiversity
or
{{Tl2|LANG=fr.|SISTER=wikisource|template name to display}} -- displays a template
on the French Wikisource sister project.